Long-haired girls who confuse the days of the week can adopt Noa`s system. But the story is also written for boys and girls with short hair – anyone can invent a sign language. On Saturday evening, before bedtime, Noa asks her mother to plait her hair in one braid, and when she wakes up next morning she knows it`s Sunday. The next day, she asks her mother to make her two braids, and that`s how she knows it`s Monday. On Tuesday, her hair is in three braids, and on Wednesday – four, and so on. One night there is a mishap, and Noa wakes up with loose hair. But she has already learnt the days of the week and doesn`t need the sign language any more.